Filter medium for air filters



July 3, 1928. A. JORDAHL FILTER MEDIUM FOR AIR FILTERS Filed Aug. 20, '1924 gme toz Anders tkr'zlahz Fleas.

Patented- July 3, 1928.

UNITED- STATES moans JORDAHL, on NEW roman. Y.

rmrnr. MEDIUM FOR .513 FILTERS.

Application filed August 20, 1824. Serial No. #538,151.

This invention relates to a filter medium for air or gas filters of the dry or seml-dry type and it specifically relates to a mediumwhich can be used either with or without a frame, which frame may constitute a filter unit. It is an object of this invention to provide a filter medium constructed of knitted flat wire to constitute a knitted metal fabric which can be easily handled and 10. washed. It'is a further object of the invention to provide a fabric of fiat metal Wire or other suitable material, so that the flat wire will be angularly arranged 1n order that a low resistance is offered to the pas- 1 sage of the air therethrough. A st1ll further object of the inventlon is to arrange any suitable number of layers of the kmtted wire fabric together so that the air Wlll have a tortuous path' therethrough, due to the angula rly arranged wires whlch at the same time will offer a very low resistance to the air. By the use of a fabric material composed of fiat metal strands in contradistlnction to such filter materials as mlneral wool, the possibility of any fibers working loose or being broken off and carnednnto the clean air duct of the filter is obviated. A .further advantage resides in the fact that the metal fabric can be stretched or pressed in order that the wire may present any de-' sired angle to the direction of the flow of the 'air. The present invention has for its principal object to prov de a novel filter medium comprising a knitted fabric, made up from flat or ribbon-like preferably metallic wire, which is employed to form a filtering body by folding the knittedfabrlc material upon itself, or by crumphng or balling up the same, or by otherwise aggrlei 40 gating sheets or layers of the same to the filtering body tov any desired mass or size. The novel metallic fabric, when knitted from flat or ribbon-like metall c wire, produces a fabric member or sheet in .45 which the flat or ribbon-like strands are twisted or turned by the formatlon of interknit loops, into constantly varying angles, so that,-when a plurality of folds, sheets or layers of such fabric are brought together to form a mass of desired size, a highly porous filter body is produced which possesses an ex ceedingly great number of intercommunieating interstices forming a. .labyrinthic structure throug the entire mass. The

filterbody thus formedmay easily be made to possess greater or less density, as the special conditions of use to which the same s put may require, because ofythe compressib1l1 ty and resiliency thereof, by virtue of which the sheets or layers of the fabric 'form- 889 mg the filter body may be either more or less loosely or more or less tightly compacted toget-her. Even when hi h ly dompressed, the twisted, or knitted metallic strands will tend to produce that irregularity or staggered relation between the loops of contacting strands of ad acent superimposed sheets or layers calculated to always assure the formation of the said labyrinthic interstices which are adapted to render the filter body pervious to the percolation therethrough of the fluid des red-to be filtered, while at the same time rendering the mass efliciently adequate to separate and capture the solid particles or impurities'desired to be removed from the fluid filtered .therethrough. Other objects w1ll be apparent from the following speci-- fication, taken in connection with the accorn panying drawing, in which like reference characters indicate like parts throughout, andin which: Q Figure 1 is an elevation of a filter unit showing a part broken away to show the filter medium. 1 I i Fig. 2 is a vertical section through the filter unit.

Fig. 3 is an elevation showing a section of the knitted flat wire fabric.

Fig. 4 is an elevation of a detail of the wire fablric of F1g.'3on agreatly enlarged scale, an,

fig. 5 is'a section taken on line 5j5 of I F g. 4.

The filter medium comprises a sheet or 5 layer 1 which is knitted from a fiat or flexible ribbon-like wire into the sheet by any suitable method. These knitted strands are of metal of such thinness and flexibility that they Wlll readily yield to the application of forces applied in the plane of the fabric' 9" sheet or at right angles to such planefor the purpose of varying the spaced relation of the adjacent strands, with respect to each other} I Referring to Figs. 3 and .4 it will be notedthat the wales of knit material are formed by" the ordinary interknitting of the loops ofeach course with the course succeeding, thus. producing a fabric having the ordinary interlooped loops. A strand .ofthis fabric comprises the side portions 2 connected integrally at each end by the loop portions3; tions conventionally shown in the drawings.

From Fig. it will be seen that the sides 2 are angularly arranged, that is they are preferably arranged angularly to the direction of the air, the arrow in Fig. 5 representing the direction of the air through an air filter. The loop portion 3 may also be angularly arranged if desired and this .is accomplished by regulating the amount of stretch which the fabric is subjected to, either before or after it is inserted into the filter frame. The amount of angularity presentedby the sides 2 and the loop 3 can be varied by stretching or pressing it. either before or after it is placed in the frame of the filter unit. Y

The sheets of wire fabric 1 are arranged in a filter unit frame 4 either in layers or in any other suitable manner. Preferably'the front and rear sides of this frame are provided with a screen 5 which is adapted to hold the sheets of fabric in place. A pair of handles 6 on the frame 4 permits of easy han- 1 5 layers. This is difierentiated from a dry filter by the fact that that type is not coatdling of the unit.

The numeral 7 indicates the edge or thickness of the wire in Fig. 4 but such thickness can of course be varied as can the width ofv the wire, since such details depend upon the service required. Due to the fact that a sheet of this medium can be stretched in any direction it can be easily packed in the frame 4; and'c'an' also be easily cleaned.- The filter which is formed by the plurality of layers of knitted fabric is preferably of the semi- ,dr'y typewhich means that the layers of'fabric are coated with a viscose material either by immersion or by otherwise coating the ed or immersed in any fluid or viscose substance and a wet filter utilizes water or the like fluid.

The sheets 1 of the air and gas filter frame may comprise knitted sheets having different size meshes, that is each sheet may have mesh of :the sheet immediately adjoiningl.

In this way the larger mesh sheets may be arranged in front or the dirty air side, and

. the handles 6 and the other side is the clean the small mesh sheets may bear-ranged in the rear, or the clean air side. On the drawing the dirty air side is the side having air side. Thus a plurality of sheets may be arranged, wherein the size of-themeshofj ifeach sheet progressively diminishes. The.

flat or ribbon-like metallic wire has runsformed into interlocked or interknit loops,

whereby the desired fabric members of width and length to-provide a suitable sur-. face area are produced- In knitting the wire to form the fabric, the same, as it is turned to shape the loops, is subjected to .more or-less torsional twisting, which-results the production offthe loop formasisting of a plurality j fabric eachlayer consisting of flexible rlb- Wire. When folds, sheets, or'layers of the fabric are aggregated into a desired mass, the thus irregularly or unevenly roughened meeting surfaces of adjacent folds, sheets of layers, more or less interlock and combine or cooperate one with another to form a structure having the intercommunicating interstices providing tortuous a-irpassages substantially uniformly distributed throughout the entire filter mass. 3

The density of the mass forming the filter body may be more or less varied, as conditions of use may re uire, by compressing the-superimposed fo ds, sheets or layers thereof more or less tightly together. liven when a mass of relatively great dens ty is desired, it may be obtained wi thout d an-- ger of losing the characteristic indlc a of the structure above described, sincethe uneven or irregularly roughenedsurfaces 0f the fabric, due to the multiplicity .of interlocked strand loops distributed thereover,

will always tend to'produce suflicient separation of the component folds, sheets or.

layers as to assure the requisite low air pressure resistance of t e structure.

It will be und'e stood that .I may use metallic wire of any kind in the production of the fabric element of the filter medium as conditions of use may require. There may be materials other than metal by which the physical characteristics of the fabric above pointed out may be attained, and which maybe found suitable for certain kinds of filtration work, hence I deem such material equivalent to metal within the scope of my present invention. It will also be understood that I may knit the. fabric from'single, double orcompounded strands as may in any special case be desirable.

*1 claim as my invention:

, 1. An air and-gas filtration medium conof layers of knitted hon-like strands forming angularl arranged bafiles to the air relative to the p ne of the layer."

2. An air and gas filtration medium consisting ofa plurality of layers of knittedfabric, each layer consisting. of ribbon-like twisted metal strands which are adapted to be irregularly" arranged relative to. the

strands of the other layers so that the loo s and side portions'of each strand form b es for the. reception "and retention. of dust pat each strand form reception and retention means for the dust particles and the irregularl arranged strands provide a tortuous for the air current. Y

4. A filter medium comprising a of layers of fabric material knitted bon-like strands, said fabric being formed plurality into a filter body providing a labyrinthic structure throughout its mass.

5. A filter medium consisting of a compressible metallic structure comprisng a plu-' rality of layers of knitted fabric, each layer comprising a multiplicity of interlocked relatively movable metallic strands adapted, under compression of the material to assume a comparatively compact relationship to each other to thereby vary the effective re-- sistance of the metallic structure to the passage of fluid therethrough.

6. A filter medium consisting of a compressible metallic structure comprisng a plurom rib-' rality of layers of knitted fabric, each layer comprising a multiplicity of flexible metallic strands connected with each other and each strand having spacedportions independent ly yieldable with "respect to the adjacent strands whereby said spaced portions of the strands may be disposed in comparatively compact relationship to eachother by com- I pression of the metallic structure to thereby vary the eflectiv'e resistance of said str'ucture' tothe pasasge of fluids therethrough.

7. In an an and as filter, a filter medium embodying a plura ity of layers of filtering material, including a metallic structure having its parts in definitely-fixed relations to each other in intercepting relation to the path of flow'of the air, and said structure consisting,

of fiat flexible metallic strands, the contiguous strands having angularly disposed interlocked loops presenting a multiplicity ofvariously inclined air bafiiing surfaces with relatively large-intervening voids, the area of said'voids and the relative angular disposition of said interlocked loops in the metallic structure being initially fixed by relatively flexing said metal strands.

In testimony whereof I afiix my signature.

- ANDERS JORDAHL. 

